Assembly Tutorial Using TASM 2.0 AND TLINK 3.0
author: mywisdom
Before start you must download assembler and linker;
http://sowiesoft.com/.../TASM.zip
Since i'm on linux now (actually developing linux perl worm) but I'm
getting so bored , so let's recall back
my old memories with tasm maybe we're gonna get some ideas on worm
on linux we can use wine to run turbo assembler 2.0
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root@mywisdom-Vostro1310:/home/mywisdom/Downloads/dos# wine tasm.exe
Turbo Assembler Version 2.0 Copyright (c) 1988, 1990 Borland
International
Syntax: TASM [options] source [,object] [,listing] [,xref]
/a,/s Alphabetic or Source-code segment ordering
/c Generate cross-reference in listing
/dSYM[=VAL] Define symbol SYM = 0, or = value VAL
/e,/r Emulated or Real floating-point instructions
/h,/? Display this help screen
/iPATH Search PATH for include files
/jCMD Jam in an assembler directive CMD (eg. /jIDEAL)
/kh#,/ks# Hash table capacity #, String space capacity #
/l,/la Generate listing: l=normal listing, la=expanded listing
/ml,/mx,/mu Case sensitivity on symbols: ml=all, mx=globals, mu=none
/mv# Set maximum valid length for symbols
/m# Allow # multiple passes to resolve forward references
/n Suppress symbol tables in listing
/o,/op Generate overlay object code, Phar Lap-style 32-bit fixups
/p Check for code segment overrides in protected mode
/q Suppress OBJ records not needed for linking
/t Suppress messages if successful assembly
/w0,/w1,/w2 Set warning level: w0=none, w1=w2=warnings on
/w-xxx,/w+xxx Disable (-) or enable (+) warning xxx
/x Include false conditionals in listing
/z Display source line with error message
/zi,/zd Debug info: zi=full, zd=line numbers only
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you dont have to use wine on blindows cmd: ms dos
* Some common used interrupts:
INT 21 H
- Interrupt 21 h function 09 h
This is one of most used interrupt, first we set 09h into ah register then
we set offset of previous declared msg into dx register. then we call dos
interrupt.
Here's sample of int 21 h function 09 h:
;fuck.asm
model small
stack 100h
data
msg db 'hei ',13,10,'$'
mov ah,9
mov dx,offset msg
int 21h
mov ah,4ch
int 21h
end
assemble:
----------------------------------
root@mywisdom-Vostro1310:/home/mywisdom/Downloads/dos# wine tasm fuck.asm
Turbo Assembler Version 2.0 Copyright (c) 1988, 1990 Borland
International
Assembling file: fuck.asm
Error messages: None
Warning messages: None
Passes: 1
Remaining memory: 431k
------------------------------------
and then linker using tlink 3.0:
----------------------------
root@mywisdom-Vostro1310:/home/mywisdom/Downloads/dos# wine tlink fuck.obj
Turbo Link Version 3.0 Copyright (c) 1987, 1990 Borland International
--------------------------
test running:
root@mywisdom-Vostro1310:/home/mywisdom/Downloads/dos# wine fuck
? ????????!?L?!hei
so what did above codes do?
;fuck.asm ---> this is a comment
model small -----------> direction here we declare that we use small
memory
stack 100h -------> stack pointer declared as 100 h (100 h bytes=80h in
words)
data -----> segment
msg db 'hei ',13,10,'$' -----> here we declare variable msg using define
bytes
mov ah,9 -----> register ah=09 hexa is required for int 21 h function 09h
mov dx,offset msg ----> move offset of msg to dx
int 21h -------------> int 21 h -> call dos
mov ah,4ch --------------> we use int 21 h function 4ch to return to
dos
int 21h ------> int 21 h function 4ch will exit to dos
end ----> end of code
